A144669 Decimal expansion of product_{n=2..infinity} (n^10-1)/(n^10+1).

9, 9, 8, 0, 1, 2, 8, 2, 6, 1, 7, 2, 9, 8, 2, 7, 8, 4, 1, 9, 0, 0, 3, 9, 8, 1, 4, 5, 0, 8, 9, 6, 8, 5, 6, 5, 5, 3, 1, 4, 5, 2, 5, 3, 8, 6, 6, 4, 3, 8, 9, 8, 4, 3, 3, 4, 7, 6, 2, 9, 4, 0, 3, 4, 9, 5, 1, 1, 7, 1, 7, 2, 8, 6, 1, 2, 5, 7, 0, 6, 6, 4, 6, 6, 2, 2, 7, 4, 4, 2, 6, 4, 4, 6, 0, 9, 0, 9, 8, 6, 6, 1, 1, 2, 2

Offset: 0

Author

R. J. Mathar, Feb 01 2009

Keywords

• nonn
• cons
• easy

Examples

			0.99801282617298278419003981450896856553...
		

Links

• J. Borwein et al., Experimentation in Mathematics, 2004, section 1.2.
• E. W. Weisstein, Infinite Product, MathWorld.

Crossrefs

Cf. A090986.

Programs

Mathematica

f[k_] := Sin[(-1)^(k/10)*Pi]; RealDigits[Pi/(5*Sinh[Pi])*Product[f[k], {k, {2, 4, 6, 8}}]/ Product[f[k], {k, {1, 3, 7, 9}}] // Re, 10, 105] // First (* Jean-François Alcover, Feb 12 2013 *)

Extensions

More terms from Jean-François Alcover, Feb 12 2013